This invention relates to vacuum deposition and includes, in particular, such deposition enhanced by bombardment of its deposits with relatively few energetic particles. Internal stress of the deposits is thereby beneficially altered and controlled and other advantages as, for example, with chromium, high reflectance can result.
U.S. Pat. No. 3,528,387 discloses an apparatus for substrate modification including cleaning that employs evaporant and ion sources. This patent does not suggest alteration of internal stress of deposited films, since its only example is with aluminum, a relatively soft metal, which deposits from vapor without normally evidencing detrimental levels of stress.
U.S. Pat. Nos. 3,904,505 and 3,961,103 disclose apparatus and process that, in one embodiment, employ together evaporant and ion sources for deposition. Stress change of deposits is not stated; and, moreover, the patents (e.g. U.S. Pat. No. 3,904,505 at column 5, lines 29-33) indicate that the ions are of such number as to contact the "neutral film atoms to be deposited" rather than the condensed film.
The article "Physics of Ion Plating and Ion Beam Deposition" by Aisenberg (inventor of U.S. Pat. No. 3,904,505 and 3,961,103 above) et al., J. Vac. Sci., Vol. 10, No. 1, Jan. 1 Feb., 1973 pp. 104-107 discloses concurrent use of evaporant and ion sources for deposition, but no mention is made of advantageous stress alteration thereby.
The article "The Compressive Stress Transition in Al, V, Zr, Nb and W Metal Films Sputtered at Low Working Pressures," by Hoffman (an inventor herein) and Thornton in THIN SOLID FILMS 45 (1977) 387-396 discloses stress alteration through sputtering at low pressures using magetron plasma confinement and also discloses that bias sputtering can alter deposit stress. There is no disclosure in this article of separately actuated sources of vapor and energetic particles.
The article "Stress in Ion-Implanted CVD Si.sub.3 N.sub.4 Films" by Eernisse in JOURNAL OF APPLIED PHYSICS, VOL. 48, No. 8, August 1977 discloses stress alteration in CVD deposits of Si.sub.3 N.sub.4 insulators on silicon using ion bombardment but fails to disclose stress alteration in metals, particularly bright metals and concomitant increase in optical reflectance.
It is believed unknown therefore, despite disclosures such as above, that internal stress and other properties as optical reflectance of deposits of metals can be altered by bombarding them with relatively few energetic particles.